KaboomJohn111

5k Engine for Ke70

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Hey all,

I very recently acquired a 5k motor and I plan to fit it to my Ke70, I know how to do the engine swap so no questions there

Since Currently the 4k in my ke70 is worked (2x 40 DCOE webers, Tighe 104 cam, 2' inch exhaust, 40 thou overbore for ACL pistons, All rotating components have been balanced, lightend flywheel, MSD 6a ignition system w/Blaster 2 coil...etc.)
I've had my hand on working 4k's...But I've honestly done a 5k before so in the interest of learning etc. I'd like to know this

What mods/specs have people built their 5k's (must be n/a, no forced induction) to, What kind of power output am I looking at (Streetable... like the 4k above)...Be realistic please, anything to lookout for (I already know 5k have hydraulic lifters, also from what i've heard the combustion chamber has more of the piston involved) so please let me know, and importantly what are the limits of the motor.

Sorry to the 5k guys in advance if I sound like a complete and utter idiot or whatever out utterances you wish to call me by

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Well, essentially you have a 4k with 80.5mm oversized pistons...a 5k.

If i were in your shoes, I would try find some flat top pistons for the 5k, use the same cam, carbs, rods, etc out of your current engine. Convert the 5k to solid cam and use your 4k head and rocker gear.That should get the compression over 10.5:1 which is nice :)

You should have a torquey little k series then

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I like the idea, but

I wish to keep the 4k together as I got a ke30 rolling chassis (which I've stripped and fixed the entire body...was pretty clean but just some boot area rust) at home and though I'd put the 4k in there and make it into a fun motorkhana car, I don't mind spending the extra money for components for the 5k,

just asking is there any particular reason to convert it to solid cam and lifters (I've noticed its a quite a common thing to do with 5k's) is it a reliability thing or something.
also what other options or specs have people built thiers to?

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solid cam just makes it go harder, better power and torque so you can see why, basically they allow for higher reving but can sound good or really shitty depending on setup also they don't work with every engine

 

some other things i would maybe suggest in investing in is bike carbs, though the weber carbs you have are good, they might hold the engine back from a bit of power, bike carbs are built for high revs so they don't break as easy and depending on the ones you get can have your engine more efficient than those webers (which to be honest isnt that hard), plus they sound amazing, look up the fellas network on youtube for a video on their bike carbs, and install, (i recently bought matts off him and I can't wait to put them on my 4K)

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I thought that even though bike carbs are great (I want to do it myself) Webers are still the go to carbs? the bike carbs are harder to get that perfect tune, also as he's running 2 they should be more than enough for higher RPMs. I could be wrong though.

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12 hours ago, Western Revheads said:

solid cam just makes it go harder, better power and torque so you can see why, basically they allow for higher reving but can sound good or really shitty depending on setup also they don't work with every engine

 

 

I call bullshit on this

As someone who ran a 5k'd KE20 motorkhana car for years, there is no reason to convert to solids.  Hydros easily copped with over 7500 rpm, even went off the tacho at times 8000+ rpm.

My combo consisted of a reground cam - a Wade 163 grind from memory, a factory twin carb manifold with modded carbs, extractors and a home made exhaust (2" system that went under the diff), and electric fan and fuel pump.  Pretty basic stuff but enough to be within 1.5 sec/km to an STI spec WRX on a dirt autocross...... and seconds ahead of a 4age powered KE35 on the same track.

 

 

 

 

 

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- I think I'll stick with the twin weber setup since they should be able to handle the job (besides If really necessary I can ask for DCOE 45's when I order the carbs)

-Since I don't have any spare 4k valve and cam gear (plus time is a bit of an issue, because job) I'll stick with the hydraulic valve and cam gear the hydraulic stuff is something new to me so may as well learn,

- I can make up a 2' inch exhaust system, but If anyone knows any extractors which fit a 5k, let me know
- I'll contact Tighe to try get a custom grind (something along the lines of a Tighe 104 because I love it, but obviously suited for hydraulic set-up, maybe with a bit more lift)...someone tell me how much lift stock 5k valve springs can take.
- I'll call up ACL pistons see if they got anything for the motor (some also let me know how much the 5k block can be bored or if it's best to leave that alone)
- I'll get all rotating components balanced
- I can send the head for a port and polish (because I lack the time to do so myself...also I am no where near as good as pete from head2head clayton)

Can someone tell me how high of a Compression ratio I can run (but must be reliable, in my head i'm thinking 10.1:1)

I'll ask some more questions once I can think up of some

But Huge Thanks for the comments so far

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Oops stuffup

Edited by coln72

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I completely agree with coln72. There is no need to convert to solid cam.

i turn my 5k to 8000rpm regularly without the need to adjust tappets (bonus).

and although I'm using a supercharger I still only need a 32/36 weber so twin side draughty wil be more than enough

(it's only a 1500cc engine) . As for the comment above about torque, I'm making 359nm

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I'll try again.

Ran a Wade 169 grind. 

Lift was 0.269"

Ex opened 75 deg closed 36 deg

Inlet opened 41 deg closed 70 deg.

Lift at TDC number 1 inlet follower 0.055"

Used standard 5k valve springs.

 

An earlier 5k ran a standard cam, but with the comp raised.lots of torque from that motor. Could go up hills one gear higher than before.

There are some YouTube videos of the ke20 in action if you search my username.

Any KE70 k motor extractors will bolt up to the 5k

 

Edited by coln72

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I suggested the solid lifter conversion as I built a 5k once with a decent cam, power would fall over just before 6000rpm. I suspected lifter "pump up", but it could have also been lack of carburation on that setup.

I also didn't like that the fixed rockers could mean rocker geometry could have been out if you deck the head and block etc, but i was lucky.

Its nice to know you guys have pushed the limits without issues

on my current build, i sent my cam to auckland cams in new zealand. Henry has 250 grinds in his computer for a k series. Haven't fired it up yet, so time will tell

 

Edited by 7000rpm

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1 hour ago, coln72 said:

Ran a Wade 169 grind. 

Lift was 0.269"

Ex opened 75 deg closed 36 deg

Inlet opened 41 deg closed 70 deg.

Lift at TDC number 1 inlet follower 0.055"

Coln, I just went and saw you vid's, you definitely went to at least 7k rpm

I think I'll stick with the Tighe 104 grind, purely because I will be using the car as my daily driver as well and although your Wade cam will give some more top end, I would like it to be more of a cruiser as I've decided to make my ke30 into my motorkhana car, since its already stripped etc.

Also coln, how did you raise the compression of your 5k (was it just a head shave) and I've been told that there are 2 different pistons (flat top and dished) and that will determine how to raise/lower compression ratio?

 

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The 5k we upped the comp on was a flat topped piston motor, so a head shave.

 

Shift light would of been on at times in those vids, so at least 7500rpm ;)

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12 hours ago, coln72 said:

Shift light would of been on at times in those vids, so at least 7500rpm ;)

wow and who said the 5k doesn't like revs

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